Handover Delay Analysis of Standalone and Non-Standalone 5G Mobile Networks

Fifth generation (5G) mobile technology has been developed to provide high data rates and ultra-low latency with reliable quality of service (QoS). In 5G mobile networks, the mobility interruption time due to the mobility of user equipment (UE) must be minimized to support real-time 5G services with high QoS performance. Handover (HO) caused by the mobility of the UE temporarily suspends data reception of the UE, which reduces the data throughput and causes mobility interruption delays. HO may occur frequently in the 5G network due to its small cell structure. Therefore, reducing the HO delay is one of the important key points of the 5G network. The 5G network has been deployed in two types of network architectures: non-standalone (NSA) and standalone (SA). Because NSA and SA networks have differences in HO procedures due to different network architecture structures, delay measurement and analysis of the HO procedure in NSA and SA networks are necessary. Therefore, this article analyzes and compares HO procedures in 5G NSA and SA networks in detail. Based on the UE log data collected through the HO field tests, the HO procedures of NSA and SA are described step by step. In addition, through HO delay measurement and comparison, delay features including U E functions are analyzed. Furthermore, HO delay histogram and probability density function (PDF) modeling through the Kolmogorov-Smirnov (K-S) tests are provided to help future HO optimization research and development.